The Stanley instrument is of interest from the point of view of the possibility of accurately measuring lengths using direct measurement methods with tapes. We present here a description of the research methods and methods for measuring lengths with the Stanley instrument in the form in which they were proposed by the author of this article and applied by him when measuring the Tsagakshinskii and Kalanguyskii baselines of the Balei-Darasun triangulation network. The Tsagakshinskii base was measured with the Stanley instrument due to the late delivery of the Jäderin-Guillaume wires. The Kalanguyskii base was measured with Jäderin-Guillaume wires; the tape was used on one section for its calibration. Calibration of the tape once again confirmed the need for long‑term study of the tape, both at the same and at different temperatures, in order to obtain a clear picture of changes in the tape. The result obtained during calibration should be considered as the first trial and the first approximation in the subsequent series of observations for studying the tape.